The spherical rolling bearings generally have two rows of rollers with a common spherical raceway in the outer race ring. On the inner race ring each roller row has its own raceway, which is inclined at an angle relative to the bearing axis. The inner race ring and the rollers can align themselves freely to different positions in the outer race ring. The bearings thereby have a self-aligning ability and allow a misalignment of shaft in relation to housing, which misalignment originates from a direction deviation at mounting or due to deflection of the shaft. The permitted misalignment is in the order of .+-.1.degree.-2.degree..
A sliding seal shall be able to take up twice the size of the misalignment at its circumference, which makes it difficult in a simple manner to secure a good sealing function. It is, therefore, unusual with built-in seals in such bearings.
Some bearings, however, have been equipped with seals such as so-called "radial seals" which exert a radial pressure against the surface on which the seal acts. On one hand, radial seals of conventional type, i.e. with one or more lips which radially abut a cylindrical surface on the inner race ring have been used. At a small misalignment such a seal produces excessively high friction at the portion which is radially compressed and a too inferior sealing effect at the opposite, elevated side. On the other hand, attempts also have been made with built-in radial seals with spherical design. An example of such a seal is shown in Swedish Patent No. 47555. A seal of this type provides an even friction independent of the size of the misalignment, but it has not been considered practical, due to complicated design, large axial space requirements and high sensibility to mechanical damage during handling. It, therefore, long has been a desire to be able to provide a seal for spherical rolling bearings, which is integrated in the bearing, which provides a good sealing effect at low friction, which is not space requiring and which seals effectively independent of the misalignment of the bearing.